U.S. patent application number 13/212503 was filed with the patent office on 2012-10-04 for rotary electric machine.
This patent application is currently assigned to MITSUBISHI ELECTRIC CORPORATION. Invention is credited to Takahiro KIMURA, Yukiyoshi OONISHI, Kazunori TANAKA.
Application Number | 20120248923 13/212503 |
Document ID | / |
Family ID | 46716724 |
Filed Date | 2012-10-04 |
United States Patent
Application |
20120248923 |
Kind Code |
A1 |
KIMURA; Takahiro ; et
al. |
October 4, 2012 |
ROTARY ELECTRIC MACHINE
Abstract
A stator winding is configured by connecting a first three-phase
stator winding and a second three-phase stator winding in parallel.
A U.sub.1-phase winding of the first three-phase stator winding is
configured by connecting a U.sub.1-1-phase winding portion and a
U.sub.1-2-phase winding portion in series, and a U.sub.2-phase
winding of the second three-phase stator winding is configured by
connecting a U.sub.2-1-phase winding portion and a U.sub.2-2-phase
winding portion in series. The U.sub.1-1-phase winding portion and
the U.sub.2-2-phase winding portion are m-turn wave windings, and
the U.sub.2-1-phase winding portion and the U.sub.1-2-phase winding
portion are n-turn wave windings (where n does not equal m). The
U.sub.1-1-phase winding portion and the U.sub.2-1-phase winding
portion are mounted into a first slot group, and the
U.sub.1-2-phase winding portion and the U.sub.2-2-phase winding
portion are mounted into a second slot group.
Inventors: |
KIMURA; Takahiro; (Tokyo,
JP) ; TANAKA; Kazunori; (Tokyo, JP) ; OONISHI;
Yukiyoshi; (Tokyo, JP) |
Assignee: |
MITSUBISHI ELECTRIC
CORPORATION
Tokyo
JP
|
Family ID: |
46716724 |
Appl. No.: |
13/212503 |
Filed: |
August 18, 2011 |
Current U.S.
Class: |
310/198 |
Current CPC
Class: |
H02K 3/28 20130101; H02K
19/22 20130101 |
Class at
Publication: |
310/198 |
International
Class: |
H02K 3/28 20060101
H02K003/28 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 1, 2011 |
JP |
2011-081885 |
Claims
1. A rotary electric machine comprising: a rotor that is rotatably
supported by a housing; and a stator comprising: a stator core in
which slots are formed at a ratio of two slots per phase per pole;
and a first three-phase stator winding and a second three-phase
stator winding that are mounted into said stator core, said stator
being supported by said housing so as to surround said rotor,
wherein: said first three-phase stator winding is configured by
wye-connecting a U.sub.1-phase winding, a V.sub.1-phase winding,
and a W.sub.1-phase winding; said second three-phase stator winding
is configured by wye-connecting a U.sub.2-phase winding, a
V.sub.2-phase winding, and a W.sub.2-phase winding; said
U.sub.1-phase winding is configured by connecting a U.sub.1-1-phase
winding portion and a U.sub.1-2-phase winding portion in series;
said V.sub.1-phase winding is configured by connecting a
V.sub.1-1-phase winding portion and a V.sub.1-2-phase winding
portion in series; said W.sub.1-phase winding is configured by
connecting a W.sub.1-1-phase winding portion and a W.sub.1-2-phase
winding portion in series; said U.sub.2-phase winding is configured
by connecting a U.sub.2-1-phase winding portion and a
U.sub.2-2-phase winding portion in series; said V.sub.2-phase
winding is configured by connecting a V.sub.2-1-phase winding
portion and a V.sub.2-2-phase winding portion in series; said
W.sub.2-phase winding is configured by connecting a W.sub.2-1-phase
winding portion and a W.sub.2-2-phase winding portion in series;
said U.sub.1-1-phase winding portion and said U.sub.2-1-phase
winding portion are mounted into a first slot group that is
constituted by said slots at intervals of six slots; said
U.sub.1-2-phase winding portion and said U.sub.2-2-phase winding
portion are mounted into a second slot group that is constituted by
said slots at intervals of six slots and that is adjacent to said
first slot group; said V.sub.1-1-phase winding portion and said
V.sub.2-1-phase winding portion are mounted into a third slot group
that is constituted by said slots at intervals of six slots; said
V.sub.1-2-phase winding portion and said V.sub.2-2-phase winding
portion are mounted into a fourth slot group that is constituted by
said slots at intervals of six slots and that is adjacent to said
third slot group; said W.sub.1-1-phase winding portion and said
W.sub.2-1-phase winding portion are mounted into a fifth slot group
that is constituted by said slots at intervals of six slots; said
W.sub.1-2-phase winding portion and said W.sub.2-2-phase winding
portion are mounted into a sixth slot group that is constituted by
said slots at intervals of six slots and that is adjacent to said
fifth slot group; said U.sub.1-1-phase winding portion, said
U.sub.2-2-phase winding portion, said V.sub.1-1-phase winding
portion, said V.sub.2-2-phase winding portion, said W.sub.1-1-phase
winding portion, and said W.sub.2-2-phase winding portion are
configured by winding conductor wires that have an identical
cross-sectional shape into respective wave windings in said slots
at intervals of six slots for m turns (where m is an integer); said
U.sub.1-2-phase winding portion, said U.sub.2-1-phase winding
portion, said V.sub.1-2-phase winding portion, said V.sub.2-1-phase
winding portion, said W.sub.1-2-phase winding portion, and said
W.sub.2-1-phase winding portion are configured by winding said
conductor wires into respective wave windings in said slots at
intervals of six slots for n turns (where n is an integer that is
different than m); and said first three-phase stator winding and
said second three-phase stator winding are connected in parallel by
connecting an output end of said U.sub.1-phase winding and an
output end of said U.sub.2-phase winding, by connecting an output
end of said V.sub.1-phase winding and an output end of said
V.sub.2-phase winding, and by connecting an output end of said
W.sub.1-phase winding and an output end of said W.sub.2-phase
winding.
2. A rotary electric machine according to claim 1, wherein a
neutral point of said first three-phase stator winding and a
neutral point of said second three-phase stator winding are not
connected.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a rotary electric machine
such as an automotive alternator, and particularly relates to a
mounting construction for a stator winding that is wound into a
wave winding in a stator core in which slots are formed at a ratio
of two slots per phase per pole.
[0003] 2. Description of the Related Art
[0004] In conventional rotary electric machines, a stator winding
is configured by wye-connecting a U-phase winding, a V-phase
winding, and a W-phase winding in each of which a first winding and
a second winding that have a phase difference of 30 electrical
degrees from each other are connected in series, and the first
winding and the second winding are each configured by connecting a
plurality of windings in parallel (see Patent Literature 1, for
example).
[0005] Patent Literature 1: Japanese Patent Laid-Open No.
2010-136459 (Gazette: FIG. 15)
[0006] In conventional rotary electric machines according to Patent
Literature 1, because the plurality of windings that constitute the
first winding and the second winding are concentrated windings,
turn counts of the windings can be changed easily. Thus, problems
with cyclic currents in parallel circuit portions can easily be
solved by making the turn counts of the plurality of windings that
are connected in parallel equal. In order to achieve desired output
characteristics, the turn count between the first winding and the
second winding that are connected in series must also be changed,
but that requirement can be met easily by changing the turn counts
of the windings that constitute the first winding and the turn
counts of the windings that constitute the second winding.
[0007] Even if the plurality of windings that constitute the first
winding and the second winding are constituted by wave windings
instead of concentrated windings, problems with the generation of
cyclic currents in the parallel circuit portions can be solved by
making the turn counts of the plurality of windings that are
connected in parallel equal, and predetermined output
characteristics can be achieved by changing the turn counts between
the first winding and the second winding that are connected in
series.
[0008] Now, let us assume that the first winding is configured by
connecting two four-turn wave windings in parallel, and the second
winding is configured by connecting two three-turn wave windings in
parallel. In that case, eight conductor wires are housed in each of
the slots in which the first winding is mounted, and six conductor
wires are housed in each of the slots in which the second winding
is mounted. Thus, the number of conductor wires that are housed in
the slots is different in each slot, and one disadvantage has been
that unevenness occurs on the inner circumferential surfaces of the
coil end groups of the stator winding, generating loud
wind-splitting noise with the rotor.
SUMMARY OF THE INVENTION
[0009] The present invention aims to solve the above problems and
an object of the present invention is to provide a rotary electric
machine in which phase windings are configured by connecting in
series two winding portions that have different turn counts to
increase output, and in which the formation of unevenness on inner
circumferential surfaces of coil end groups is suppressed to enable
wind-splitting noise to be reduced.
[0010] In order to achieve the above object, according to one
aspect of the present invention, there is provided a rotary
electric machine including: a rotor that is rotatably supported by
a housing; and a stator including: a stator core in which slots are
formed at a ratio of two slots per phase per pole; and a first
three-phase stator winding and a second three-phase stator winding
that are mounted into the stator core, the stator being supported
by the housing so as to surround the rotor. The first three-phase
stator winding is configured by wye-connecting a U.sub.1-phase
winding, a V.sub.1-phase winding, and a W.sub.1-phase winding, and
the second three-phase stator winding is configured by
wye-connecting a U.sub.2-phase winding, a V.sub.2-phase winding,
and a W.sub.2-phase winding. The U.sub.1-phase winding is
configured by connecting a U.sub.1-1-phase winding portion and a
U.sub.1-2-phase winding portion in series, the V.sub.1-phase
winding is configured by connecting a V.sub.1-1-phase winding
portion and a V.sub.1-2-phase winding portion in series, the
W.sub.1-phase winding is configured by connecting a W.sub.1-1-phase
winding portion and a W.sub.1-2-phase winding portion in series,
the U.sub.2-phase winding is configured by connecting a
U.sub.2-1-phase winding portion and a U.sub.2-2-phase winding
portion in series, the V.sub.2-phase winding is configured by
connecting a V.sub.2-1-phase winding portion and a V.sub.2-2-phase
winding portion in series, and the W.sub.2-phase winding is
configured by connecting a W.sub.2-1-phase winding portion and a
W.sub.2-2-phase winding portion in series. The U.sub.1-1-phase
winding portion and the U.sub.2-1-phase winding portion are mounted
into a first slot group that is constituted by the slots at
intervals of six slots, the U.sub.1-2-phase winding portion and the
U.sub.2-2-phase winding portion are mounted into a second slot
group that is constituted by the slots at intervals of six slots
and that is adjacent to the first slot group, the V.sub.1-1-phase
winding portion and the V.sub.2-1-phase winding portion are mounted
into a third slot group that is constituted by the slots at
intervals of six slots, the V.sub.1-2-phase winding portion and the
V.sub.2-2-phase winding portion are mounted into a fourth slot
group that is constituted by the slots at intervals of six slots
and that is adjacent to the third slot group, the W.sub.1-1-phase
winding portion and the W.sub.2-1-phase winding portion are mounted
into a fifth slot group that is constituted by the slots at
intervals of six slots, and the W.sub.1-2-phase winding portion and
the W.sub.2-2-phase winding portion are mounted into a sixth slot
group that is constituted by the slots at intervals of six slots
and that is adjacent to the fifth slot group. The U.sub.1-1-phase
winding portion, the U.sub.2-2-phase winding portion, the
V.sub.1-1-phase winding portion, the V.sub.2-2-phase winding
portion, the W.sub.1-1-phase winding portion, and the
W.sub.2-2-phase winding portion are configured by winding conductor
wires that have an identical cross-sectional shape into respective
wave windings in the slots at intervals of six slots for m turns
(where m is an integer), and the U.sub.1-2-phase winding portion,
the U.sub.2-1-phase winding portion, the V.sub.1-2-phase winding
portion, the V.sub.2-1-phase winding portion, the W.sub.1-2-phase
winding portion, and the W.sub.2-1-phase winding portion are
configured by winding the conductor wires into respective wave
windings in the slots at intervals of six slots for n turns (where
n is an integer that is different than m). The first three-phase
stator winding and the second three-phase stator winding are
connected in parallel by connecting an output end of the
U.sub.1-phase winding and an output end of the U.sub.2-phase
winding, by connecting an output end of the V.sub.1-phase winding
and an output end of the V.sub.2-phase winding, and by connecting
an output end of the W.sub.1-phase winding and an output end of the
W.sub.2-phase winding.
[0011] According to the present invention, the U.sub.1-1-phase
winding portion that constitutes the U.sub.1-phase winding and the
U.sub.2-1-phase winding portion that constitutes the U.sub.2-phase
winding are wound into the first slot group, and the
U.sub.1-2-phase winding portion that constitutes the U.sub.1-phase
winding and the U.sub.2-2-phase winding portion that constitutes
the U.sub.2-phase winding are wound into the second slot group.
Thus, the number of conductor wires that are housed in each of the
slots of the first slot group is (m+n), and the number of conductor
wires that are housed in each of the slots of the second slot group
is (m+n). Thus, the number of conductor wires that are housed in
each of the slots is equal, suppressing formation of unevenness on
inner circumferential surfaces of the coil end groups of the stator
winding. Generation of wind-splitting noise that results from
interference between the rotating rotor and the inner
circumferential surfaces of the coil end groups is thereby
suppressed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a longitudinal cross section that shows an
automotive alternator according to a preferred embodiment of the
present invention;
[0013] FIG. 2 is an electrical circuit diagram for the automotive
alternator according to the preferred embodiment of the present
invention;
[0014] FIG. 3 is a connection diagram for a stator winding in the
automotive alternator according to the preferred embodiment of the
present invention;
[0015] FIG. 4 is an end elevation that shows a stator core that is
used in the automotive alternator according to the preferred
embodiment of the present invention;
[0016] FIG. 5 is a partial end elevation that explains a state in
which conductor wires are mounted into the stator core in the
automotive alternator according to the preferred embodiment of the
present invention;
[0017] FIG. 6 is a graph that shows measured results of output
characteristics of the automotive alternator according to the
preferred embodiment of the present invention;
[0018] FIG. 7 is a connection diagram for a stator winding
according to a comparative example; and
[0019] FIG. 8 is a partial end elevation that explains a state in
which conductor wires are mounted into a stator core in an
automotive alternator according to the comparative example.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0020] A preferred embodiment of the present invention will now be
explained with reference to the drawings.
[0021] FIG. 1 is a longitudinal cross section that shows an
automotive alternator according to a preferred embodiment of the
present invention, FIG. 2 is an electrical circuit diagram for the
automotive alternator according to the preferred embodiment of the
present invention, FIG. 3 is a connection diagram for a stator
winding in the automotive alternator according to the preferred
embodiment of the present invention, FIG. 4 is an end elevation
that shows a stator core that is used in the automotive alternator
according to the preferred embodiment of the present invention, and
FIG. 5 is a partial end elevation that explains a state in which
conductor wires are mounted into the stator core in the automotive
alternator according to the preferred embodiment of the present
invention. Moreover, 1, 7, etc., through 67 in FIG. 4 represent
slot numbers. FIG. 5 represents a state in which an annular stator
core is cut open and spread out in a plane.
[0022] In FIG. 1, an automotive alternator 1 that functions as a
rotary electric machine includes: a housing 4 that is constituted
by a front bracket 2 and a rear bracket 3 that are each
approximately bowl-shaped and made of aluminum; a shaft 6 that is
rotatably supported in the housing 4 by means of bearings 5; a
pulley 7 that is fixed to an end portion of the shaft 6 that
extends out frontward from the housing 4; a rotor 8 that is fixed
to the shaft 6 and that is disposed inside the housing 4; a stator
20 that is fixed to the housing 4 so as to surround the rotor 8; a
pair of slip rings 12 that are fixed to a rear end of the shaft 6,
and that supply electric current to the rotor 8; a pair of brushes
13 that slide on respective surfaces of the slip rings 12; a brush
holder 14 that accommodates the brushes 13; a rectifier 15 that is
electrically connected to the stator 20 so as to convert
alternating current that is generated by the stator 20 into direct
current; and a voltage regulator 16 that is mounted onto the brush
holder 14, and that adjusts magnitude of an alternating-current
voltage that is generated by the stator 20.
[0023] The rotor 8 includes: a field coil 9 that generates magnetic
flux on passage of an excitation current; a pole core 10 that is
disposed so as to cover the field coil 9, and in which magnetic
poles are formed by the magnetic flux; and the shaft 6, which is
fitted centrally through the pole core 10. Fans 11 are fixed to two
axial end surfaces of the pole core 10 by welding, etc.
[0024] The stator 20 is held from two axial ends by the front
bracket 2 and the rear bracket 3, and includes: a stator core 21
that is disposed so as to surround the pole core 10 so as to ensure
a uniform gap from an outer peripheral surface of the pole core 10
of the rotor 8; and the stator winding 22, which is mounted to the
stator core 21.
[0025] As shown in FIG. 4, the stator core 21 is a laminated core
that is formed into a cylindrical shape by laminating a
predetermined number of core segments that are formed by punching
thin magnetic steel plates into annular shapes, and integrating the
laminated predetermined number of core segments by welding, for
example. The stator core 21 has: an annular core back portion 21a;
tooth portions 21b that each extend radially inward from an inner
peripheral surface of the core back portion 21a, and that are
arranged at a uniform angular pitch circumferentially; and slots
21c that are bounded by the core back portion 21a and adjacent
tooth portions 21b.
[0026] Here, the number of claw-shaped magnetic poles in the pole
core 10 of the rotor 8 is twelve, and the number of slots 21c is
seventy-two. Specifically, the slots 21c are formed at a ratio of
two slots per phase per pole, and at a uniform angular pitch
circumferentially (an electrical pitch of .pi./6).
[0027] As shown in FIGS. 2 and 3, the stator winding 22 is
configured by connecting together output ends of the three phases
of the first three-phase stator winding 23 and the second
three-phase stator winding 24 to connect the first three-phase
stator winding 23 and the second three.sup.-phase stator winding 24
in parallel.
[0028] The first three-phase stator winding 23 is configured by
wye-connecting a U.sub.1-phase winding 30, a V.sub.1-phase winding
31, and a W.sub.1-phase winding 32. The U.sub.1-phase winding 30 is
configured by connecting in series a U.sub.1-1-phase winding
portion 41 and a U.sub.1-2-phase winding portion 42 that have a
phase difference of 30 electrical degrees. The V.sub.1-phase
winding 31 is configured by connecting in series a V.sub.1-1-phase
winding portion 43 and a V.sub.1-2-phase winding portion 44 that
have a phase difference of 30 electrical degrees. The W.sub.1-phase
winding 32 is configured by connecting in series a W.sub.1-1-phase
winding portion 45 and a W.sub.1-2-phase winding portion 46 that
have a phase difference of 30 electrical degrees.
[0029] The second three-phase stator winding 24 is configured by
wye-connecting a U.sub.2-phase winding 35, a V.sub.2-phase winding
36, and a W.sub.2-phase winding 37. The U.sub.2-phase winding 35 is
configured by connecting in series a U.sub.2-1-phase winding
portion 51 and a U.sub.2-2-phase winding portion 52 that have a
phase difference of 30 electrical degrees. The V.sub.2-phase
winding 36 is configured by connecting in series a V.sub.2-1-phase
winding portion 53 and a V.sub.2-2-phase winding portion 54 that
have a phase difference of 30 electrical degrees. The W.sub.2-phase
winding 37 is configured by connecting in series a W.sub.2-1-phase
winding portion 55 and a W.sub.2-2-phase winding portion 56 that
have a phase difference of 30 electrical degrees.
[0030] An output end of the U.sub.1-phase winding 30 and an output
end of the U.sub.2-phase winding 35 are connected, an output end of
the V.sub.1-phase winding 31 and an output end of the V.sub.2-phase
winding 36 are connected, and an output end of the W.sub.1-phase
winding 32 and an output end of the W.sub.2-phase winding 37 are
connected. The first three-phase stator winding 23 and the second
three-phase stator winding 24 are thereby connected in parallel to
configure the stator winding 22.
[0031] Next, a specific construction of the stator winding 22 will
be explained.
[0032] The U.sub.1-1-phase winding portion 41 is a three-turn wave
winding that is formed by winding a conductor wire 29 into a wave
winding in a first slot group that is constituted by the slots 21c
at intervals of six slots that include Slot Numbers 1, 7, etc.,
through 61, and 67. The U.sub.1-2-phase winding portion 42 is a
four-turn wave winding that is formed by winding a conductor wire
29 into a wave winding in a second slot group that is constituted
by the slots 21c at intervals of six slots that include Slot
Numbers 2, 8, etc., through 62, and 68.
[0033] The V.sub.1-1-phase winding portion 43 is a three-turn wave
winding that is formed by winding a conductor wire 29 into a wave
winding in a third slot group that is constituted by the slots 21c
at intervals of six slots that include Slot Numbers 3, 9, etc.,
through 63, and 69. The V.sub.1-2-phase winding portion 44 is a
four-turn wave winding that is formed by winding a conductor wire
29 into a wave winding in a fourth slot group that is constituted
by the slots 21c at intervals of six slots that include Slot
Numbers 4, 10, etc., through 64, and 70.
[0034] The W.sub.1-1-phase winding portion 45 is a three-turn wave
winding that is formed by winding a conductor wire 29 into a wave
winding in a fifth slot group that is constituted by the slots 21c
at intervals of six slots that include Slot Numbers 5, 11, etc.,
through 65, and 71. The W.sub.1-2-phase winding portion 46 is a
four-turn wave winding that is formed by winding a conductor wire
29 into a wave winding in a sixth slot group that is constituted by
the slots 21c at intervals of six slots that include Slot Numbers
6, 12, etc., through 66, and 72.
[0035] The U.sub.2-1-phase winding portion 51 is a four-turn wave
winding that is formed by winding a conductor wire 29 into a wave
winding in the first slot group. The U.sub.2-2-phase winding
portion 52 is a three-turn wave winding that is formed by winding a
conductor wire 29 into a wave winding in the second slot group.
[0036] The V.sub.2-1-phase winding portion 53 is a four-turn wave
winding that is formed by winding a conductor wire 29 into a wave
winding in the third slot group. The V.sub.2-2-phase winding
portion 54 is a three-turn wave winding that is formed by winding a
conductor wire 29 into a wave winding in the fourth slot group.
[0037] The W.sub.2-1-phase winding portion 55 is a four-turn wave
winding that is formed by winding a conductor wire 29 into a wave
winding in the fifth slot group. The W.sub.2-2-phase winding
portion 56 is a three-turn wave winding that is formed by winding a
conductor wire 29 into a wave winding in the sixth slot group.
[0038] The U.sub.1-phase winding 30 is configured by joining a
winding finish portion of the U.sub.1-1-phase winding portion 41
and a winding start portion of the U.sub.1-2-phase winding portion
42 by tungsten-inert gas (TIG) welding, etc., and is a seven-turn
winding. Similarly, the V.sub.1-phase winding 31 and the
W.sub.1-phase winding 32 are also seven-turn wave windings. Then,
the winding start portions of the U.sub.1-1-phase winding portion
41, the V.sub.1-1-phase winding portion 43, and the W.sub.1-1-phase
winding portion 45 are joined by TIG welding, etc., to form the
first three-phase stator winding 23.
[0039] The U.sub.2-phase winding 35 is a seven-turn wave windings
that is configured by connecting the U.sub.2-1-phase winding
portion 51 and the U.sub.2-2-phase winding portion 52 in series.
Similarly, the V.sub.2-phase winding 36 and the W.sub.2-phase
winding 37 are also seven-turn wave windings. Then, the winding
start portions of the U.sub.2-1-phase winding portion 51, the
V.sub.2-1-phase winding portion 53, and the W.sub.2-1-phase winding
portion 55 are joined by TIG welding, etc., to form the second
three-phase stator winding 24.
[0040] In addition, winding finish portions of the U.sub.1-2-phase
winding portion 42 and the U.sub.2-2-phase winding portion 52 are
joined by TIG welding, etc., winding finish portions of the
V.sub.1-2-phase winding portion 44 and the V.sub.2-2-phase winding
portion 54 are joined by TIG welding, etc., and winding finish
portions of the W.sub.1-2-phase winding portion 46 and the
W.sub.2-2-phase winding portion 56 are joined by TIG welding, etc.,
to form the stator winding 22.
[0041] Next, operation of the automotive alternator 1 that is
configured in this manner will be explained.
[0042] First, an electric current is supplied from a battery (not
shown) through the brushes 13 and the slip rings 12 to the field
coil 9 of the rotor 8 to generate magnetic flux. Magnetic poles are
formed in the claw-shaped magnetic poles of the pole core 10 by
this magnetic flux.
[0043] At the same time, rotational torque from an engine is
transferred to the shaft 6 by means of a belt (not shown) and the
pulley 7 to rotate the rotor 8. Thus, rotating magnetic fields are
applied to the stator winding 22 in the stator 20 to generate
electromotive forces in the stator winding 22. The alternating
currents that are generated by these electromotive forces are
rectified into a direct current by the rectifier 15, to charge the
battery, or be supplied to an electrical load.
[0044] In the stator winding 22 that is configured in this manner,
the two winding portions of each of the phases that are connected
in parallel all have seven turns, suppressing the generation of
cyclic currents in the parallel circuit portions.
[0045] As shown in FIG. 5, seven conductor wires 29 are housed
inside each of the slots 21c. Thus, the number of conductor wires
29 that are housed in each of the slots 21c is equal, suppressing
the formation of unevenness on the inner circumferential surfaces
of the coil end groups of the stator winding 22. Generation of
wind-splitting noise that results from interference between the
rotating rotor 8 and the inner circumferential surfaces of the coil
end groups is thereby suppressed.
[0046] Because the neutral points between the first three-phase
stator winding 23 and the second three-phase stator winding 24 are
each configured by connecting three conductor wires 29, work for
connecting together the neutral points between the first
three-phase stator winding 23 and the second three-phase stator
winding 24 is extremely complicated. In the present invention,
because the neutral points between the first three-phase stator
winding 23 and the second three-phase stator winding 24 are not
connected with each other, the complicated connecting work can be
omitted, facilitating manufacturing of the stator 20.
[0047] In the respective phase windings, because two winding
portions that are offset by 30 electrical degrees, such as the
U.sub.1-1-phase winding portion 41 and the U.sub.1-2-phase winding
portion 42, for example, are connected in series, magnetomotive
pulsating forces can be reduced, reducing magnetic noise.
[0048] In the respective phase windings, because the turn counts in
the two winding portions that are connected in series, such as the
U.sub.1-1-phase winding portion 41 and the U.sub.1-2-phase winding
portion 42, for example, are different, output from the automotive
alternator 1 can be increased.
[0049] Here, results when output characteristics of the present
automotive alternator 1 were measured are shown in FIG. 6.
Moreover, in FIG. 6, the solid line represents the output
characteristics of the present automotive alternator 1, and the
broken line represents the output characteristics of a comparative
automotive alternator. The comparative automotive alternator is
configured in a similar manner to that of the present automotive
alternator 1 except that a comparative stator winding 60 that is
shown in FIG. 7 is used.
[0050] As can be seen from FIG. 6, it has been confirmed that the
automotive alternator 1 can achieve higher output than the
comparative automotive alternator throughout a range of rotational
speeds.
[0051] Next, a specific construction of the comparative stator
winding 60 will be explained with reference to FIGS. 7 and 8.
Moreover, FIG. 7 is a connection diagram for a stator winding
according to the comparative example, and FIG. 8 is a partial end
elevation that explains a state in which conductor wires are
mounted into a stator core in an automotive alternator according to
the comparative example. Moreover, FIG. 8 represents a state in
which an annular stator core is cut open and spread out in a
plane.
[0052] A U.sub.1-1-phase winding portion 71 is a four-turn wave
winding that is formed by winding a conductor wire 29 into a wave
winding in the first slot group. A U.sub.1-2-phase winding portion
72 is a three-turn wave winding that is formed by winding a
conductor wire 29 into a wave winding in the second slot group.
[0053] A V.sub.1-1-phase winding portion 73 is a four-turn wave
winding that is formed by winding a conductor wire 29 into a wave
winding in the third slot group. A V.sub.1-2-phase winding portion
74 is a three-turn wave winding that is formed by winding a
conductor wire 29 into a wave winding in the fourth slot group.
[0054] A W.sub.1-1-phase winding portion 75 is a four-turn wave
winding that is formed by winding a conductor wire 29 into a wave
winding in the fifth slot group. A W.sub.1-2-phase winding portion
76 is a three-turn wave winding that is formed by winding a
conductor wire 29 into a wave winding in the sixth slot group.
[0055] A U.sub.2-1-phase winding portion 81 is a four-turn wave
winding that is formed by winding a conductor wire 29 into a wave
winding in the first slot group. A U.sub.2-2-phase winding portion
82 is a three-turn wave winding that is formed by winding a
conductor wire 29 into a wave winding in the second slot group.
[0056] A V.sub.2-1-phase winding portion 83 is a four-turn wave
winding that is formed by winding a conductor wire 29 into a wave
winding in the third slot group. A V.sub.2-2-phase winding portion
84 is a three-turn wave winding that is formed by winding a
conductor wire 29 into a wave winding in the fourth slot group.
[0057] A W.sub.2-1-phase winding portion 85 is a four-turn wave
winding that is formed by winding a conductor wire 29 into a wave
winding in the fifth slot group. A W.sub.2-2-phase winding portion
86 is a three-turn wave winding that is formed by winding a
conductor wire 29 into a wave winding in the sixth slot group.
[0058] A U-phase winding 61 is configured by connecting in series a
winding portion in which the U.sub.1-1-phase winding portion 71 and
the U.sub.2-1-phase winding portion 81 are connected in parallel
and a winding portion in which the U.sub.1-2-phase winding portion
72 and the U.sub.2-2-phase winding portion 82 are connected in
parallel. A V-phase winding 62 is configured by connecting in
series a winding portion in which the V.sub.1-1-phase winding
portion 73 and the V.sub.2-1-phase winding portion 83 are connected
in parallel and a winding portion in which the V.sub.1-2-phase
winding portion 74 and the V.sub.2-2-phase winding portion 84 are
connected in parallel. A W-phase winding 63 is configured by
connecting in series a winding portion in which the W.sub.1-1-phase
winding portion 75 and the W.sub.2-1-phase winding portion 85 are
connected in parallel and a winding portion in which the
W.sub.1-2-phase winding portion 76 and the W.sub.2-2-phase winding
portion 86 are connected in parallel.
[0059] As shown in FIG. 7, the stator winding 60 is configured by
wye-connecting the U-phase winding 61, the V-phase winding 62, and
the W-phase winding 63, and forms an electrical circuit that is
approximately equivalent to that of the stator winding 22 described
above.
[0060] The comparative automotive alternator is configured using
the stator winding 60 instead of the stator winding 22. In the
stator winding 60 that is configured in this manner, the turn
counts of the two winding portions that constitute the respective
parallel circuit portions are also equal, suppressing the
generation of cyclic currents in the parallel circuit portions.
Because two winding portions that are offset by 30 electrical
degrees are connected in series in each of the phase windings,
magnetomotive pulsating forces can be reduced, reducing magnetic
noise.
[0061] However, in the automotive alternator according to the
comparative example, slots 21c in which eight conductor wires 29
are housed and slots 21c in which six conductor wires 29 are housed
are arranged alternately, as shown in FIG. 8. Thus, unevenness
arises on the inner circumferential surface of the coil end groups
of the stator winding 22, increasing wind-splitting noise that
results from interference between the rotating rotor 8 and the
inner circumferential surfaces of the coil end groups.
[0062] Moreover, in each of the above embodiments, explanations are
given for automotive alternators, but the present invention is not
limited to automotive alternators, and similar effects are also
exhibited if the present invention is applied to automotive rotary
electric machines such as automotive electric motors, automotive
generator-motors, etc.
[0063] In the above embodiment, phase windings are configured by
connecting in series two winding portions that have a phase
difference of 30 electrical degrees, but the phase difference
between the two winding portions that are connected in series is
not limited to 30 (electrical) degrees.
[0064] In the above embodiment, respective phase windings of the
first and second three-phase stator windings are configured by
connecting a four-turn winding portion and a three-turn winding
portion in series, but the turn counts of the two winding portions
that are connected in series are not limited to four turns and
three turns, provided that they are different than each other.
* * * * *